Newb means a newbie, a new player to game.Noob means a newbie that behaves in a way he doesnt deserves respect. If thats not the case, then user of term just is disrespectful without reasonScrub means player who doesnt want to evolve own gameplay, instead choosing to devolve gameplay of his opponents (like prohibiting certain actions by calling them "cheap" and calling opponent an "cheater"), and so from view of pro player, scrub is ridiculous.